I don't tend to match the front to the back on my personal quilts. So if I have enough leftovers then ill piece a back. I've bought the ugliest thing on the clearance rack(@ 50 cents a yard), used muslin, extra wide backs, other quilt tops. Others talk about vintage sheets because the flats don't have wear like the fitted. Depends on what your artistic desire is. If you have a chance to see antique museum quilts, they often have something odd on the back. To me it's charming.